Blank holder device for a drawing device for producing hollow cylindrical bodies

ABSTRACT

A blank holder device for a drawing device, for example a drawing press. The blank holder device has a blank holder sleeve, which, in a predetermined position exerts a blank holder force on a blank part. The sleeve is fastened to a head part and is stationary relative to it. To move the blank holder sleeve in a stroke direction, the head part is borne, through a head part guiding arrangement, at least at two front guide locations, to undergo translational motion in a stroke direction, and it is braced to be essentially stationary in all directions at right angles to the stroke direction. On the side opposite the blank holder sleeve, the head part is connected with at least one drive element of the blank holder drive device and that can, together with the head part, be moved by a motor and a coupling arrangement in the stroke direction.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefits of German Application No. 10 2017 106 356.0 filed Mar. 24, 2017. The said German application No. 10 2017 106 356.0 is incorporated herein by reference in its entirety as though fully set forth.

BACKGROUND OF THE INVENTION

The invention relates to a blank holder device for a drawing device for producing hollow cylindrical bodies, such as, for instance can bodies, in particular for pressurized containers/cans or beverage cans. The shaping performed by means of the drawing device is done by ironing, for example. The blank part for this, also called a “cup”, can be a bowl-shaped or cup-shaped piece that has been shaped in a first shaping step. The blank part can also be a plate-shaped, for example round, sheet metal part, that can be called a “blank”. The blank part can be shaped into a hollow cylindrical body using a drawing punch or a ram of the machine or press. The hollow cylindrical body has a bottom and, made of the same material, a wall that is closed in a peripheral direction and that is connected with the bottom without a seam or joint. On the side opposite the bottom, the hollow cylindrical body is open. To allow a drawing punch to shape the preferably cup-shaped blank part, there is a blank holder device. The blank holder device has a blank holder sleeve with a sleeve end face which, when in a blank holder position, presses the blank part against a clamping surface with a blank holder force and projects, e.g., into the cup-shaped blank part. Starting from this clamped position, the drawing punch then performs the shaping, for example by ironing.

Such shaping devices are known in the art. DE 28 43 742 A1 shows a punch arrangement for ironing, wherein a medium flows through the punch arrangement to control the temperature of the ironed container and the punch arrangement, to reduce shrinkage of the container on the punch and to make stripping easier.

The device disclosed in DE 25 19 521 A1 has a blank holder sleeve of a blank holder device, this blank holder sleeve being arranged coaxial with a drawing punch. The blank holder can be moved relative to the drawing punch by pressurization of a pressure chamber, and is arranged so that it is guided on the drawing punch.

DE 601 15 640 T2 discloses a blank holder device wherein the blank holder is hydraulically driven. The blank holder can be moved along a main axis. ‘Extending laterally offset to the main axis are piston rods of a hydraulic drive cylinder, these piston rods fluidically subdividing a movable cylinder housing that is guided along the piston rods into two work working chambers. Depending on the pressurization of the chambers, the cylinder housing can be moved relative to the piston rods. The cylinder housing is connected with the blank holder or the blank holder sleeve.

US 2016/0318089 A1 also shows a shaping device with a blank holder. The blank holder has a head part on which the blank holder sleeve is arranged. On a side of the head part opposite the blank holder sleeve there are drive rods which can move the head part and the blank holder sleeve in a stroke direction. The drive rods are borne so that they are movable in the stroke direction.

Other shaping devices are also disclosed in, for example, DE 60 2004 009 954 T2, DE 42 18 497 A1, or DE 69 610 910 T2.

The blank holder devices known from the prior art have turned out to be insufficiently precise. The wall thickness of the hollow cylindrical container that is formed can fluctuate. The wall thickness tolerances lie in the micron range. During production, insufficient precision can lead to an undesirably high proportion of rejects. Therefore, it can be considered the goal of this invention to create an improved blank holder device that has sufficient accuracy and reduces the proportion of rejects among the hollow cylindrical bodies that are produced.

SUMMARY OF THE INVENTION

This is accomplished by a blank holder device having the features of the claims. The invention relates to a blank holder device 22 for a drawing device 10, for example a drawing press. The blank holder device 22 has a blank holder sleeve 43, which, when in a blank holder position II, exerts a blank holder force FN on a blank part 14. The blank holder sleeve 43 is fastened to a head part 23 and is stationary relative to it. To move the blank holder sleeve 43 in a stroke direction H, the head part 23 is directly borne, through a head part guiding arrangement 50, at least at two front guide locations 51, so that it can undergo translational motion in stroke direction H, and it is braced so that it is essentially stationary in all directions at right angles to the stroke direction H. Every front guide location 51 is preferably formed by a head part guiding unit 52 with a guide element 53 extending in the stroke direction H. The head part 52 is guided directly along the guide elements 53. On the side opposite the blank holder sleeve 43, the head part 23 is connected with at least the one drive element 25 that belongs to the blank holder drive device 24 and that can, together with the head part 23, be moved by means of a motor 31 and a coupling arrangement 30 in the stroke direction H.

The inventive blank holder device has a blank holder sleeve fastened to a head part. The blank holder sleeve has, on the side opposite the head part, a sleeve end face which, when the blank holder sleeve is in a blank holder position, is set up to press a blank part, for example a cup-shaped blank part, against a clamping surface with a specified blank holder force, especially a blank holder force that is controllable by open-loop or closed-loop control. If the blank part is cup-shaped, the blank holder sleeve can, when in its blank holder position, project into the cup-shaped blank part. The blank part can also be in the form of a flat, preferably circular sheet metal part.

The blank holder device has a blank holder drive device with at least one drive element that can be made to undergo translational motion in a stroke direction. The drive element can be in the form of a drive bar or a drive rod, for example. The front end of the drive element is connected with the head part, and starting from the head part it extends away in the stroke direction toward a back end on the side opposite the blank holder sleeve. The blank holder drive device is set up to move the head part and, along with it, also the blank holder sleeve in the stroke direction by moving the at least one drive element. The blank holder sleeve can execute a movement between an initial position and the blank holder position.

The blank holder device has a head part guiding arrangement. The head part guiding arrangement is set up to bear the head part at least at two front guide locations so that it can undergo translation motion in the stroke direction, and to brace it against movements in all other degrees of freedom. Thus, the front head part guiding arrangement allows the head part to undergo only translational motion in a single degree of freedom. The head part guiding arrangement is passive and is not set up to move the head part or to produce a driving force acting on the head part. The head part guiding arrangement preferably acts directly on the head part.

The head part is guided, by means of the head part guiding arrangement, in one translational degree of freedom near or on the level of the blank holder sleeve when viewed in the stroke direction, and the head part is braced in all other degrees of freedom. This allows very exact positioning of the blank holder sleeve when it is in the blank holder position, or very exact movement of the blank holder sleeve into the blank holder position. Hollow cylindrical bodies, in particular can bodies, must be produced with a specified wall thickness having tolerances in the micron range. The invention is based on the knowledge that to accomplish this, the blank holder sleeve must, when it is in its blank holder position, exert the same blank holder force onto the blank part at every location on the sleeve end face. A blank holder sleeve that is inclined or tilted with respect to the stroke direction or to a main axis can, even at small angles of tilt or inclination, produce a blank holder force that is not uniform in the peripheral direction around the main axis or along the entire sleeve end face. This in turn leads to deviations in wall thickness and to rejects when producing hollow cylindrical bodies. Therefore, the head part is not only indirectly guided and driven through the blank holder drive device, but rather a head part guiding arrangement is additionally present, which exactly guides the head part at least at two front guide locations. The head part guiding arrangement transfers no driving forces to the head part. This allows very exact guiding at the front guide locations. This in turn exactly positions the blank holder sleeve, in particular in its blank holder position, and reduces the number of rejects when hollow cylindrical bodies are produced.

The head part is preferably plate-shaped.

The head part guiding arrangement can have at least two head part guiding units, every one of which is present to form a guide location. At least two of the front guide locations that are present or the head part guiding units that are present are preferably arranged with a transverse spacing to one another in a transverse direction at right angles to the stroke direction. In a preferred embodiment, every head part guiding unit has a guide element extending in the stroke direction and a guide bearing part that is movable relative to it. For example, the guide element can be formed by a guide rod and the guide bearing part can surround the guide rod at the respective front guide location. It is preferred that the guide bearing part form a guide sleeve that completely surrounds, or essentially completely surrounds, the guide rod. At every front guide location the guide bearing unit in question can form a plain bearing or a roller bearing.

If there are more than two front guide locations, for example four front guide locations, they can form two groups, which are arranged with a spacing to one another in the transverse direction. In the stroke direction, the front guide locations of a common group can be arranged so that they are aligned.

It is preferred that the guide bearing parts of the head part guiding units be arranged on the head part and that the guide elements or the guide rods be arranged on a machine frame or a machine base of the blank holder device. For example, the head part can extend from one of the guide elements to another one of the guide elements in a transverse direction at right angles to the stroke direction. Alternatively, the head part could also have the guide elements or the guide rods arranged on it, and the guide bearing parts could be arranged on the machine frame or on the machine base.

The blank holder device preferably also has a drive guide arrangement. The drive guide arrangement is set up to bear the at least one drive element of the blank holder drive device so that it can undergo translational motion at least at one back guide location. At this at least one back guide location, the at least one drive element can be movable in only one degree of freedom and be braced in all other degrees of freedom.

In one embodiment, there are at least two drive elements, which are borne at least at one back guide location so that the drive guide arrangement can make them undergo translational motion in the stroke direction. A transverse spacing of the back guide locations in a transverse direction at right angles to the stroke direction can be smaller than the transverse spacing of the front guide locations of the head part guiding arrangement. This allows, on the side of the head part opposite the blank holder sleeve, an arrangement of the blank holder drive device that occupies little space in the transverse direction.

In a preferred embodiment, the blank holder drive device has a motor and a coupling arrangement, this coupling arrangement being directly coupled, at a coupling location, with the at least one drive element, and making a drive connection between the motor and the at least one drive element. The coupling arrangement transfers a driving force from the drive motor to the at least one drive element. This driving force can act on the at least one drive element at an angle to the stroke direction.

In one sample embodiment, each drive element is borne at a back guide location between the coupling location, at which the coupling arrangement acts, and the head part. Alternatively or in addition, every drive element can extend away from the head part in the stroke direction, starting from the coupling location, toward a back end, and be borne at a back guide location between the coupling location and the back end.

The head part preferably has a central through opening for a drawing punch that is arranged so that it can be moved along a main axis in the stroke directions. Through the central through opening and the blank holder sleeve, the drawing punch can act on the cup-shaped blank part and shape it with the help of a die tool. In particular, the blank holder sleeve is arranged coaxial with the main axis or to the drawing punch.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantageous embodiments of the invention follow from the claims, the description, and the drawings. Preferred sample embodiments of the blank holder device are explained below using the attached drawings. The figures are as follows:

FIG. 1 a schematic block diagram-like representation of a sample embodiment of a drawing device or drawing press with a sample embodiment of a blank holder device with a blank holder sleeve, which is located in an initial position;

FIG. 2 a partial representation of FIG. 1, wherein the blank holder sleeve of the blank holder device is located in a blank holder position;

FIG. 3 a schematic perspective representation of a sample embodiment of a blank holder sleeve;

FIG. 4 a schematic block diagram-like representation of a sample embodiment of a blank holder drive device;

FIG. 5 a schematic block diagram-like representation of another sample embodiment of a blank holder drive device;

FIG. 6 a perspective representation of a part of a sample embodiment of a blank holder device with a head part, a head part guiding arrangement, and two drive elements of a blank holder drive device;

FIG. 7 a sample embodiment of a blank holder device with the head part, the head part guiding arrangement, and the drive elements according to FIG. 6; and

FIG. 8 a perspective representation of another sample embodiment of a blank holder device with additional back guide locations for the drive elements.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a block diagram of a sample embodiment of a drawing device 10, which can also be referred to as a drawing press. The drawing device 10 has a drawing punch 12, which can also be referred to as a ram, that is arranged so that it can be moved by means of a drawing punch drive 11 along a main axis A in a stroke direction H. A front end 13 of the drawing punch 12 forms a so-called “punch” and acts on a blank part 14 (cup), which according to the example is cup-shaped or bowl-shaped, and shapes it into a hollow cylindrical body using a die tool 15. In the sample embodiment, the die tool 15 has an ironing channel 16, which is arranged coaxial with the main axis A and has a entrance opening 16 a and an exit opening 16 b. The ironing channel 16 has multiple ironing dies 17 along it that are arranged coaxial with the main axis A. The inside diameters of the ironing dies 17 are different, and become smaller the closer the ironing die 17 is located to the exit opening 16 b. The die tool 15 is also referred to as a “toolpack”.

The drawing punch 12 can shape the blank part 14 by ironing. This involves the drawing punch 12 moving the blank part 14 through the ironing channel 16 and the ironing dies 17, forming a hollow cylindrical body with a bottom and a wall that is connected to the bottom and that has a specified wall thickness. In the area of the exit opening 16 b of the ironing channel 16 there can be a stripper 18, which is only very schematically illustrated and which is set up to strip the hollow cylindrical body that has been shaped from the drawing punch 12 when the latter executes a return stroke back through the ironing channel 16.

The drawing device 10 also includes a blank holder device 22. The blank holder device 22 has a head part 23 that can be made to undergo translational motion in stroke direction H. To move the head part 23 there is a blank holder drive device 24 comprising at least one drive element 25 that can be made to undergo translational motion in stroke direction H. According to the example, there are two such drive elements 25, which are formed by drive rods 26. Each drive rod 26 has a front end, with which it is fastened to head part 23. Starting from the front end 27, each drive rod 26 extends away from head part 23 in stroke direction H toward a back end 28.

According to the example, the head part 23 is made as an integral part from one body, without a seam or joint. It can be plate-shaped.

At a coupling location 29, every drive element 25 or every drive rod 26 is directly coupled with a coupling arrangement 30 (FIGS. 4 and 5). The coupling arrangement 30 makes a drive connection between a motor 31 of the blank holder drive device 24 and the drive elements 25, and, according to the example, the drive rods 26. The coupling arrangement 30 can have different designs. At the coupling location 29, it acts directly on the at least one drive element 25 and is set up to convert a rotation of the motor 31 into a translational motion of the respective drive element 25 in stroke direction H.

In the very schematic sample embodiment of the blank holder drive device 24 illustrated in FIG. 4, the motor 31 drives an eccentric 32. The eccentric 32 acts on a coupling element 33 that is pivotably borne at a pivot bearing location 34 between the coupling location 29 and the cam 32. The eccentric 32 is movably guided along the coupling element 33. At the coupling location 29, a coupling pin 35 connected with the drive element 25 is also movably guided along the coupling element 33. Rotation of the eccentric 32 about the axis of rotation of the motor 31 causes the coupling element 33 to swivel on the coupling location 29 and causes translational motion of the coupling pin 35 together with the drive element 25 in question or with the drive rod 26 in question.

In departure from the illustration according to FIG. 4, it is also possible for the eccentric 32 to be connected with a connecting rod-like coupling element 33, which is arranged so that it can pivot at a location between the eccentric 32 and the coupling location 29 and is guided so that it can be moved in the direction in which the connecting rod-like coupling element extends. Such an arrangement can also cause the at least one drive element 25 to move in stroke direction H.

Another example of a blank holder drive device 24 is schematically shown in FIG. 5. In departure from the previous sample embodiments, coupling arrangement 30 is in the form of a knee lever arrangement. In this embodiment, the coupling element 33 is rotatably supported on the eccentric 32, on the one hand, and, on the other hand, rotatably supported on a knee joint. At the knee joint 36, a first knee lever 37 and a second knee lever 38 are connected together in an articulated manner. The end of first knee lever 37 opposite the knee joint 36 is supported in an articulated manner on a machine frame or a machine base 39. The end of second knee lever 38 opposite the knee joint 36 is arranged in an articulated manner on coupling pin 35. Rotation of the eccentric 32 about the axis of rotation of the motor 31 changes the knee angle between the two knee levers 37, 38 at the knee joint 36, which can cause the at least one drive element 25 to move in the stroke direction H.

The above-described sample embodiments of the coupling arrangement 30 allow the motor 31 to be arranged at a right angle to the stroke direction H, offset to at least one drive element 25, for example on the level of the at least one drive element 25, when viewed in stroke direction H. A possible variation of this is for the motor 31 also to be arranged behind the at least one drive element 25, when viewed in stroke direction H. In this case, coupling element 33 of the coupling arrangement 30 can be, for example, a connecting rod.

The head part 23 has a blank holder sleeve 43 fastened to it. The blank holder sleeve 43 is arranged coaxial with the main axis A. It is located on the side of the head part 23 facing away from the at least one drive element 25. Starting from the head part 23, the blank holder sleeve 43 extends toward a free end, on which there is a sleeve end face 44 that forms an annulus that is concentric with the main axis A. A normal vector of the end face 44 extends in the stroke direction H parallel to the main axis A (FIG. 3). On the side opposite the sleeve end face 44, the blank holder sleeve has, for example a mounting flange 45, by means of which it can be detachably fastened, for example by means of a threaded connection, to a fastening surface 46 of the head part 23. The fastening surface 46 extends in a plane at right angles to stroke direction H.

The head part 23 is borne, by means of a head part guiding arrangement 50, at least at two front guide locations 51—according to the example exactly two front guide locations 51, so that it can undergo translational motion in the stroke direction H. In the sample embodiment, the head part guiding arrangement 50 allows only translational motion in the stroke direction H, and prevents movement in other translational degrees of freedom and, in the sample embodiment, also in all rotational degrees of freedom. The two guide locations 51 are arranged with a first transverse spacing d1 in a transverse direction Q at right angles to the stroke direction H. According to the example, every guide location 51 is formed by a head part guiding unit 52, these head part guiding units 52 being best shown in FIG. 6. The head part guiding units 52 are arranged on opposite sides, in the transverse direction Q, with respect to the main axis A or the drawing punch 12.

Every head part guiding unit 52 has a guide element 53 extending in stroke direction H, each of which in the sample embodiment is formed by a guide rod 54. Every guide element 53 has a guide bearing part 55 borne at it so that this guide bearing part 55 can be moved in the stroke direction H. According to the example, each guide bearing part 55 surrounds, in the shape of a sleeve, the guide rod 54 that is associated with it. The guide bearing part 55 is solidly connected with the head part 23. The guide elements 53 or guide rods 54 of the head part guiding units 52, of which there are two according to the example, are solidly connected with the machine frame or machine base 39, for example by means of the supports 56 illustrated in FIG. 6.

In the sample embodiment, the head part 23 is essentially plate-shaped with a ring-shaped middle part 57, that has an projection 58 on each of its sides that are opposite in the transverse direction Q. Every projection 58 has a through hole in it, in which a guide bearing part 55 of a respective head part guiding unit 52 is seated. The guide bearing part 55 can form a plain bearing or a rolling bearing at the front mounting point 51 in question. Alternatively, it is also possible to arrange the guide rods 26 on the head part 23 and the guide bearing parts 55 on the machine base 39.

In departure from the described embodiment, every head part guiding unit 52 can also form a group with multiple guide locations 51, which can be arranged next to one another, for example aligned with one another, in the stroke direction. The two groups of guide locations 51 are arranged on opposite sides of the main axis A, with spacing in the transverse direction Q.

In the middle part 57 of head part 23 there is a central through opening 59, which is symmetrically arranged with respect to main axis A and is aligned with the cylindrical passage of the blank holder sleeve 43. The central through opening 59 allows the drawing punch 12 to pass through the head part 23.

The blank holder drive device 24 can move the head part 23 together with the blank holder sleeve 43 in stroke direction H, so that the blank holder sleeve 43 moves between an initial position I (FIG. 1) and a blank holder position II (FIG. 2). In the blank holder position II, the blank holder sleeve 43 projects into the blank part 14, which is cup-shaped according to the example, so that the sleeve end face 44 lies against a bottom of the blank part 44 and presses the bottom against a clamping surface 62 with a blank holder force FN. The clamping surface 62 is in the shape of a ring around the entrance opening 16 a of the ironing channel 16 on the die tool 15. Alternatively to the sample embodiment shown, it is also possible for a plate-shaped blank part to be pressed, by the blank holder sleeve 43, against the clamping surface 62 with the blank holder force FN.

In FIG. 1 and FIGS. 7 and 8 it can also be seen that in addition to the head part guiding arrangement 50 there is also a drive guide arrangement 63, which is set up to guide the drive element 25 or the drive rods 26 in stroke direction H. Every drive element 25 is translationally guided by the drive guide arrangement 63 at least at one back guide location 64. According to the example, the drive guide arrangement 63 has a main guide body 65 which is arranged on the machine base 39 and has a plain bearing or rolling bearing sleeve for a drive rod 26 or a drive element 25 at each back guide location 64. At the back guide location 64, a drive rod 26 completely passes through the main guide body 65. The main guide body 65 is arranged between the coupling location 29 and the head part 23. The back guide locations 64 are arranged with a spacing from the head part 23 in the stroke direction H. In the transverse direction Q, the back guide locations 64 in the main guide body 65 have a second transverse spacing d2, which is smaller than the first transverse spacing d1 between the two front guide locations 51 of the head part guiding arrangement 50.

The drawing punch 12 can be borne at the main guide body 65 also, such that it is movably guided in the stroke direction H. For this purpose, the main guide body 65 in the sample embodiment has a drawing punch guide sleeve 66 arranged on it, which extends away from the main guide body 65 in the stroke direction H on the side opposite the head part 23.

In the sample embodiment illustrated in FIG. 7, the drive elements 25 or the drive rods 26 are only borne on one back guide location 64 each. In the sample embodiment illustrated in FIGS. 1 and 8, each drive element 25 is borne at two back guide locations 64. For this purpose, it is possible to arrange, on the machine base 39, an additional guide body 67 for each of them with a plain bearing or rolling bearing sleeve, the associated drive element 25 extending through the additional guide body 67, which is borne there at another back guide location 64 so that it is movable in the stroke direction H. The coupling location 29 is preferably arranged between the two back guide locations 64 of a drive element 25.

As has already been explained, in the sample embodiment described here there are two drive elements 25 or two drive rods 26, which are fastened to the head part 23. In FIGS. 6 through 8 it can be seen that the two drive elements 25 can be connected together through a connection unit 70 at their respective coupling location 29. The connection unit 70 creates a solid connection between the two drive elements 25. This can ensure that the driving force is uniformly introduced onto the head part 23 through the two drive elements 25 and additionally reduces the danger of tilting or gouging. The connection unit 70 can be closed, for example, in the shape of a ring around the main axis A. In the area of the main axis A, the connection unit 70 has a passage 71 for the drawing punch 12 or the drawing punch guide sleeve 66 (FIGS. 7 and 8). According to the example, the passage 71 is in the form of a central guide for the drawing punch 12.

As an alternative to the sample embodiments in FIGS. 6 and 7, the connection unit 70 can also have a different shape, for example it can be closed in the shape of a semi-ring (FIG. 8). This eliminates the passage and a resulting central guide.

The drawing device 10 works as follows:

First, a blank part 14, which is cup-shaped according to the example, is positioned on the clamping surface 62 of the die tool 15 so that the open side facing away from the bottom is facing the drawing punch 12 and the blank holder sleeve 43. The blank holder drive device 24 moves the head part 23, and with it the blank holder sleeve 43, out of its initial position I into the blank holder position II in which the sleeve end face 44 presses on the edge of the bottom directly adjacent to the wall inside the blank part 14 and presses this bottom edge against the clamping surface 62 with a clamping force F. In the blank holder position II, the blank holder force FN can be controlled, e.g., through a bellows cylinder of the blank holder drive device 24 and a gas or air pressure prevailing in the bellows cylinder.

Simultaneously with or following the movement of the blank holder sleeve 43 into the blank holder position II, the front end 13 of the drawing punch 12 is moved against and, according to the example, into the cup-shaped blank part 14, and lies against the bottom of the blank part 14. As soon as the blank holder sleeve 43 has reached its blank holder position II and exerts the required blank holder force FN, the drawing punch 12, driven by means of the drawing punch drive 11, moves or draws the blank part 14 into the ironing channel 16 and moves it through the ironing dies 17. During this ironing, the blank part 14 is shaped into a hollow cylindrical body that has a specified wall thickness. The inside diameter of the hollow cylindrical body that is shaped corresponds to the outside diameter of the drawing punch 12 following its front end 13.

Once the drawing punch 12 has moved the shaped hollow cylindrical body completely through the ironing channel 16, this drawing punch 12 is moved, by means of the drawing punch drive 11, back through the ironing channel 16 in the stroke direction H. While this is happening, the hollow cylindrical body that has been shaped is stripped off the drawing punch 12 by means of the stripper 18. The drawing punch drive 11 moves the drawing punch 12 back into its initial position.

The blank holder drive device 24 moves the blank holder sleeve 43 back into its initial position I after the blank part 14 has been pulled completely into the ironing channel 16 in the first phase of the shaping and is no longer acted upon by the blank holder sleeve 43.

When the blank holder sleeve 43 assumes its initial position I and the drawing punch 12 also assumes its initial position after the shaping, a new blank part 14 can be loaded.

In order to achieve the required tolerance of the wall thickness of the hollow cylindrical body that has been shaped, it is necessary that the blank holder sleeve 43 exert a very uniform blank holder force FN along its entire periphery. Therefore, very exact alignment of the blank holder sleeve 43 coaxial with the main axis A or positioning of the sleeve end face 44 at right angles to the main axis A is required. FIGS. 4 and 5 schematically illustrate that the coupling arrangement 30 can exert a driving force FA on the drive pin 35 or the drive elements 25 at an angle to the main axis A, this driving force FA having a driving force component FP parallel to the main axis A and a driving force component FR at right angles to the main axis A. This introduction of the driving force FA at an angle to the main axis A presents the danger that the drive elements 25 and the head part 23 incline or tilt the blank holder sleeve 43 relative to the main axis A, so that the blank holder sleeve 43 is not exactly coaxially positioned about the main axis A and the sleeve end face 44 is not aligned exactly at a right angle to the main axis A. According to the invention, the alignment of the blank holder sleeve 43 is clearly improved by the head part guiding arrangement 50. The head part 23 is directly borne at multiple front guide locations 51 by the head part guiding units 52 so that it is movably guided in the stroke direction H, while the head part 23 is braced by the head part guiding arrangement 50 against movements in all other degrees of freedom. This also makes it possible to tolerate a driving force FA on the drive elements 25 that is introduced in a direction not parallel to the main axis A or not in the stroke direction H. The danger of misalignment of the blank holder sleeve 43 is reduced or avoided. The result is a blank holder force FN that is uniform in the peripheral direction about the main axis A, which in turn leads to a very uniform wall thickness of the hollow cylindrical body that is shaped, and prevents rejects in production, or reduces their number.

In the sample embodiments illustrated here, the stroke direction H or the main axis A are horizontally oriented. Alternatively, the stroke direction H can also be oriented in the vertical direction or at an angle to the vertical and horizontal directions.

As is very schematically illustrated in FIG. 1 by the dashed line, the drawing punch drive 11 and the blank holder drive device 24 can be electronically and/or mechanically coupled with one another. It is also possible for only a single motor to be present, whose rotation is used both to move the drawing punch 12 and also to move the blank holder sleeve 43 or the head part 23.

The invention relates to a blank holder device 22 for a drawing device 10, for example a drawing press. The blank holder device 22 has a blank holder sleeve 43, which, when in a blank holder position II, exerts a blank holder force FN on a blank part 14. The blank holder sleeve 43 is fastened to a head part 23 and is stationary relative to it. To move the blank holder sleeve 43 in a stroke direction H, the head part 23 is directly borne, through a head part guiding arrangement 50, at least at two front guide locations 51, so that it can undergo translational motion in stroke direction H, and it is braced so that it is essentially stationary in all directions at right angles to the stroke direction H. Every front guide location 51 is preferably formed by a head part guiding unit 52 with a guide element 53 extending in the stroke direction H. The head part 52 is guided directly along the guide elements 53. On the side opposite the blank holder sleeve 43, the head part 23 is connected with at least the one drive element 25 that belongs to the blank holder drive device 24 and that can, together with the head part 23, be moved by means of a motor 31 and a coupling arrangement 30 in the stroke direction H.

LIST OF REFERENCE NUMBERS

-   10 Drawing device -   11 Drawing punch drive -   12 Drawing punch -   13 Front end of the drawing punch -   14 Blank part -   15 Die tool -   16 Ironing channel -   16 a Entrance opening -   16 b Exit opening -   17 Ironing die -   18 Stripper -   22 Blank holder device -   23 Head part -   24 Blank holder drive device -   25 Drive element -   26 Drive rod -   27 Front end of the drive rod -   28 Back end of the drive rod -   29 Coupling location -   30 Coupling arrangement -   31 Motor -   32 Eccentric -   33 Coupling element -   34 Pivot bearing location -   35 Coupling pin -   36 Knee joint -   37 First knee lever -   38 Second knee lever -   39 Machine base -   43 Blank holder sleeve -   44 Sleeve end face -   45 Fastening flange -   46 Fastening surface of the head part -   50 Head part guiding arrangement -   51 Front guide location -   52 Head part guiding unit -   53 Guide element -   54 Guide rod -   55 Guide bearing part -   56 Support -   57 Middle part of the head part -   58 Projection -   59 Central through opening -   62 Clamping surface -   63 Drive guide arrangement -   64 Back guide location -   65 Main guide body -   66 Drawing punch guide sleeve -   67 Additional guide body -   70 Connection unit -   71 Passage -   I Initial position -   II Blank holder position -   A Main axis -   d1 First transverse spacing -   d2 Second transverse spacing -   FA Driving force -   FN Blank holder force -   FP Driving force component parallel to the main axis -   FR Driving force component at right angles to main axis -   H Stroke direction -   Q Transverse direction 

What is claimed is:
 1. A blank holder device (22) for a drawing device (10) for producing hollow cylindrical bodies, with a blank holder sleeve (43) that is fastened to a head part (23), with a blank holder drive device (24) that has at least one drive element (25) that is translation-movable in a stroke direction (H) at which the head part (23) is arranged, the blank holder drive device (24) being adapted to move the blank holder sleeve (43) in a stroke direction (H) between an initial position (I) and a blank holder position (II), the blank holder sleeve (43) having a sleeve end face (44) that, in the blank holder position (II), presses a blank part (14) with a blank holder force (F) against a clamping surface (62), with a head part guiding arrangement (50) that is adapted to translation-movably bear the head part (23) in the stroke direction (H) at least at two front guide locations (51), and to support it against movements in other degrees of freedom.
 2. A blank holder device according to claim 1, characterized in that the head part guiding arrangement (50) has at least two head part guiding units (52), each of which has a guide element (53) extending in a stroke direction (H) and a guide bearing part (55) slidably borne at it.
 3. A blank holder device according to claim 2, characterized in that the guide element (53) is formed by a guide rod (54) and that the guide bearing part (55) surrounds the guide rod (54) at the respective front guide location (51).
 4. A blank holder device according to claim 2, characterized in that the guide bearing parts (55) of the head part guiding units (52) are arranged at the head part (23) and that the guide elements (53) are arranged at a machine frame or a machine base (39).
 5. A blank holder device according to claim 4, characterized in that the head part (23) extends in a transverse direction (Q) at a right angle to the stroke direction (H) from one of the guide elements (53) to another one of the guide elements (53).
 6. A blank holder device according to claim 2, characterized in that two of the at least two front guide locations (51) of the head part guiding arrangement (52) are arranged with a first transverse spacing (d1) in a transverse direction (Q) at right angles to the stroke direction (H).
 7. A blank holder device according to claim 1, characterized in that a drive guide arrangement (63) is provided that bears the at least one drive element (25) of the blank holder drive device (24) translation-movable at least at one back guide location (64).
 8. A blank holder device according to claim 7, characterized in that at least two drive elements (25) are provided, each of which is translation-movably borne at a back guide location (64) by the drive guide arrangement (63), a second transverse spacing (d2) of the back guide locations (64) being smaller in a transverse direction (Q) at a right angle to the stroke direction (H) than a first transverse spacing (d1) of the front guide locations (51) of the head part guiding arrangement (50).
 9. A blank holder device according to claim 7, characterized in that the back guide locations (64) are arranged with a spacing to the head part (23) in a stroke direction (H).
 10. A blank holder device according to claim 1, characterized in that the blank holder drive device (24) has a motor (31) and a coupling arrangement (30), that is coupled with the at least one drive element (25) at a coupling location (29), and creating a drive connection between the motor (31) and the at least one drive element (25).
 11. A blank holder device according to claim 7, characterized in that the blank holder drive device (24) has a motor (31) and a coupling arrangement (30), that is coupled with the at least one drive element (25) at a coupling location (29), and creating a drive connection between the motor (31) and the at least one drive element (25), every drive element (25) is borne at a back guide location (64) between the coupling location (29) and the head part (23).
 12. A blank holder device according to claim 11, characterized in that every drive element (25) extends away from the head part (23) in a stroke direction (H), starting from the coupling location (29), toward a back end (28), and is borne at a back guide location (64) between the coupling location (29) and the back end (28).
 13. A blank holder device according to claim 1, characterized in that the head part (23) has a central through opening (71) for a drawing punch (12) that is arranged movably along a main axis (A) in the stroke direction (H).
 14. A blank holder device according to claim 10, characterized in that the blank holder sleeve (43) is arranged coaxial with the main axis (A).
 15. A blank holder device according to claim 7, characterized in that the blank holder drive device (24) has a motor (31) and a coupling arrangement (30), that is coupled with the at least one drive element (25) at a coupling location (29), and creating a drive connection between the motor (31) and the at least one drive element (25), every drive element (25) extends away from the head part (23) in a stroke direction (H), starting from the coupling location (29), toward a back end (28), and is borne at a back guide location (64) between the coupling location (29) and the back end (28). 